I. Technical Field
The present invention relates to a display device including a light source device and a screen, in particular, to a light source device for a display device capable of being separated from the display device and used alone. Furthermore, the present invention relates to a method for adjusting an image of the display device.
II. Description of Related Art
FIG. 10 is a schematic view showing one example of a conventional portable display device. A lamp 51 is accommodated in a light source device 50. The white light output from lamp 51 is branched into lights of red, green, and blue using optical filters 54a to 54g, wave combined by a prism 56 after being transmitted through a liquid crystal panel 55, transmitted through a lens 57, and projected onto a screen 58 to be produced as an image.
FIG. 11 is a schematic view showing equipment that can be connected to the conventional display device as shown in Japanese Patent Laid-open Publication No. 2003-215562 (FIG. 1). An image signal is input in the display device of the conventional example through an RGB terminal. In addition, any equipment having the output terminal for the RGB signal can be connected to the display device. For example, personal computer 201, such as notebook PC, video game machine 202, optical disc player 203, such as various types of DVD, optical disc recorder 204, including VTR all-in-one type, camera integrated VTR 205, stationary VTR 206, BS/CS tuner 207, TV 208, hard disc recorder 209, including all-in-one of various types of optical disc drives, Internet broadcasting Set Top Box (STB) 210, CATV STB 211, terrestrial digital broadcasting STB 212, BS HDTV broadcasting STB 213, and the like may be connected to the display device. Moreover, the display device may include D4 input terminal, DVI-D input terminal, IEEE 1394 terminal, component terminal, S terminal, video terminal, and the like arranged in accordance with the format of the signal output from the equipment connected to the display device.
Since a lamp is used as a light source, the power consumption is large and the power supply from a plug outlet is necessary for portable use in the conventional configuration. The device is also too large. Furthermore, the conventional front projection type display device only has a function of front projection, and cannot be used as a rear projection type device. Thus, a wide space is necessary in the projection. In addition, the screen for the front projection type display device only has the function of receiving the irradiated light from the display device, and the image adjustment must be performed by a user.
Another problem is speckle noise generated when a coherent light source (e.g., laser) is used as a light source. When projecting laser light or coherent light on a screen to produce an image, the laser light reflected from the screen interferes, thereby generating the speckle noise. The image appears as glaring and contrast is produced in the image due to the speckle noise. Consequently, the quality of the projected image becomes lower, which makes an observer uncomfortable and causes tiredness, and thus greatly lowers the product's value.